Answer: The equations are correct as the addition of individual and group acts must be equal to the total duration of the act.
Explanation
As the addition of individual and group acts must be equal to the total duration of the acts, then, the equations should be:
[tex]12x+6y=120[/tex][tex]4x+y=30[/tex]
which is equal to what the classmates wrote. Thus, they are correct.
